Field of the Invention
The present invention relates to a metal frame for a device equipped with a wireless charging transmitter or receiver and, most particularly, to a metal frame for a device being equipped with a wireless charging transmitter or receiver including a plurality of perforation holes configured in at least one partial area of the metal frame, wherein the perforation hole has a diameter ranging from sub nm to several μm, and wherein an average distance between an arbitrary point A on a circumferential surface of a perforation hole, among the plurality of perforation holes, and an arbitrary point B on a circumferential surface of another perforation hole being adjacent to the perforation hole is equal to or less than a skin depth corresponding to a metallic material of the metal frame, and wherein point A and point B respectively correspond to points indicating a longest distance between the circumferential surfaces of each perforation hole to which point A and point B belong.
Discussion of the Related Art
The wireless charging technology has evolved at a remarkable rate and is being extensively applied in diverse types of appliances including mobile phones. Such wireless charging may also be referred to as non-contact charging and may be broadly divided into two different types: a method using electromagnetic induction and a method using magnetic resonance. The electromagnetic induction type charging technology corresponds to a method of charging batteries by generating an induced current between a charging pad and two coils provided inside a mobile phone. And, the charging method using magnetic resonance corresponds to a method of performing charging by sending out power through the same frequency to a transmitting/receiving end that is located at a distance 1 to 2 meters (m) away from the charging system.
The electromagnetic induction type charging method may be used in mobile devices, such as mobile phones, laptop computers, and so on, and also in electric vehicles. And, as the currently most widely used technology, the electromagnetic induction type charging method may use frequencies ranging from several hundreds of kilohertz (kHz) to several tens of megahertz (MHz). And, most particularly, in order to perform wireless charging of mobile phones, the electromagnetic induction type charging method generally uses frequencies within a range of 100 to 300 kHz.
Meanwhile, manufacturers of mobile devices, such as mobile phones, have consistently developed their technologies in order to maximize the performance of their mobile devices and, eventually, achieved their goal of realizing a state-of-the-art mobile device technology. Therefore, it has become more difficult for the manufacturers to create their own distinguished functions that are related to the performance of the device. Accordingly, the manufacturers are becoming more focused on the design of their mobile devices, and, therefore, the selection of the material for a frame configuring the outside feature of the mobile device has become one of the most important issues.
More specifically, until recently, in order to manufacture light-weight mobile devices, the manufacturers have mostly fabricated their mobile devices by using plastic material. However, due to the characteristics of the plastic material, there were limitations in realizing high-quality texture in the mobile devices. Accordingly, manufacturers are gradually seeking to replace the frames of their mobile devices to metal frames, which can provide diverse texture and more enhanced durability. Evidently, metal frames may be disadvantageous in the aspect of weight as compared to the plastic frames. However, due to the excellence in the design provided by the metal frame, the difference in weight between the two materials may not be significant.
Since near field communication (NFC) and diverse means of payment, such as Samsung Pay, and so on, which are mostly equipped in the mobile device, are operated by a frequency band sufficient enough to pass through metal, these may not be required to be considered when selecting the material for fabricating the frame of a mobile device. Nevertheless, since metal acts as a shielding material that blocks out the frequency band for performing wireless charging, a problem of being incapable of performing wireless charging may occur.
More specifically, as one of the functions included in the wireless charging technology, there exists a function of detecting metallic objects potentially causing danger that are within a close range of the wireless charging receiver via digital feedback between the wireless charging receiver and transmitter. This function is referred to as foreign object detection (FOD), and, when a foreign object is detected, the power transmission is stopped (or interrupted). Until recently, the frame for devices that are mostly used has been fabricated by using plastic material. Since a power line cannot pass through insulators (or non-conductors), such as plastic, heat may not be generated, or an extremely low level of heating may be performed. Accordingly, the foreign object detection function may not be performed. Therefore, as long as the plastic frame is applied to the mobile devices, problem may not occur in the wireless power transmission.
Heat (temperature) that is generated from a foreign object (metal) may correspond to a standard for detecting foreign objects when electronic magnetic waves are generated from a coil. And, when detecting the temperature that is generated from the foreign object (metal), as described above, and when the detected temperature is equal to or higher than a predetermined standard (generally 60° C.), the wireless charging system stops (or interrupts) the power transmission. Accordingly, there lies a disadvantage of not being able to apply a frame configured of a metallic material to a device that is equipped with a wireless charging transmitter or receiver.
Therefore, in order to comply with the mainstreaming of adopting metal frames to the external features of diverse devices, such as mobile devices, research and development of a frame enabling wireless charging despite the usage of a metal frame is urgently required.